The traditional space re-entry vehicle for astronauts includes two principal components. The first component was a re-entry vehicle of the Gemini or Apollo types which included an astronaut cabin and heat shield section which protected the cabin from high temperatures encountered during re-entry. Detachable propulsion units were attached to such re-entry vehicles so as to obtain a correct re-entry trajectory. After such a trajectory was obtained, the propulsion package would separate. This type of traditional space vehicle had a fixed design based upon a particular planned re-entry along a prescribed trajectory.
With the progression of space travel, plans are now underway for the construction of large Space Stations where astronauts will live and work for protracted periods of time. Although regular shuttle travel between Earth and a Space Station will be possible with vehicles such as the Space Shuttle, a need exists for enabling emergency escape by a Space Station crew to Earth.
It has been conceived that a traditional type of re-entry vehicle could be employed which includes a propulsion unit and a crew cabin. However, it would be highly desirable if a re-entry vehicle could be adaptable for a host of other tasks from the Space Station, other than emergency escape and return to Earth.